Presently known optical spectrometers include a dispersion means, such as a prism or diffraction grating, which is effectively rotated in an optical path between a point source being spectrometrically analyzed and an image plane containing a detector for the source. These spectrometers are based on the principle that different wavelengths of the source being analyzed are deflected by differing amounts by the dispersion means. As the dispersion means is effectively rotated, different wavelengths of the source are passed through a slit positioned in front of the image plane, whereby the angular position of the dispersion means at any instant of time can be correlated with the wavelength of energy passing through the slit to a detector in the image plane. Devices utilizing a rotating dispersion means have generally been utilized only for detecting the position of stationary optical sources. Dispersive devices that have been designed for providing a spectrometric analysis of a moving optical source have generally required servomechanisms for pointing the analyzer at the source. For many applications, such analyzers are not wholly satisfactory because they require an initial knowledge of the source angular position to enable the device to be pointed directly at the source. If the angular position of the source in a field of view is initially unknown, such analyzers are generally incapable of detecting the presence of the source and enabling the source spectral content to be determined.